The objective of this study is to evaluate the validation of quality of care measurements that assesses clinical 'process', by comparing these process measures with functional and physiological end results. This will be studied in the context of acute myocardial infarction: the study will document the care given or prescribed by physicians and received by patients with acute myocardial infarction in order to determine whether measurable differences in these actions result in clinically significant differences in these patients' health status six months later. Acute myocardial infarction is judged an appropriate condition to test out this strategy on account of its relatively high frequency, its major impact upon patient's survival and function, the substantial variation that exists in its current management, and the ease of identification of an appropriate inception cohort of study patients. The action of physicians and their interactions with patients will be measured for consecutive admissions of patients with acute myocardial infarction to specified community hospital coronary care units both during their hospitalization and at follow-up visits to their physicians' offices. Physician actions will be assessed both by chart review and questionnaires completed by the patients, his/her family and the physician; the validation of these measurements will be carried out as part of this study. These assessments will include a new measure for assessing interpersonal processes relating to patient education. The functional and clinical outcomes of the patients (adjusted for prognostic features of their illness) will be assessed up to and at six months after the acute myocardial infarction, and the data set will be analyzed for associations between outcomes and clinical processes. The analysis will provide useful new knowledge in two areas: first, it will provide an assessment of the effects of differences in the clinical management of patients with acute myocardial infarction. Second, it ill supply useful data on the feasibility of this evaluation strategy for use in studying other diseases.